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\begin{equation*} \rho \cdot \left({\partial v \over \partial t}+ u {\partial v \over \partial x}+ v {\partial v \over \partial y}+ w {\partial v \over \partial z}\right) = k_y -{\partial p \over \partial y} + {\partial \over \partial y} \left[ \mu \cdot \left(2 \cdot {\partial v \over \partial y}-\frac{2}{3}\cdot (\nabla \cdot \mathbf{v}) \right) \right] + {\partial \over \partial z}\left[\mu \cdot \left({\partial v \over \partial z} + {\partial w \over \partial y}  \right) \right] + {\partial \over \partial x}\left[\mu \cdot \left({\partial u \over \partial y} + {\partial v \over \partial x}  \right) \right]\end{equation*}
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